Hi Our Exchange2007 has been installed on load balancing environment (2 HUB/CAS 2007 servers) and clustered mailboxes (2 mailboxes) all servers are running Windows 2008 , and we have 3 ADs in our domain controller. One of our Mailboxes server gives a repeated error in Windows eventlog: Process MSEXCHANGEADTOPOLOGYSERVICE.EXE (PID=2192). Topology discovery failed, error 0x80040952 (LDAP_LOCAL_ERROR (Client-side internal error or bad LDAP message)). Look up the Lightweight Directory Access Protocol (LDAP) error code specified in the event description. To do this, use Microsoft Knowledge Base article 218185, "Microsoft LDAP Error Codes." Use the information in that article to learn more about the cause and resolution to this error. Use the Ping or PathPing command-line tools to test network connectivity to local domain controllers. I tried to ping and telnet our ADs ( and domain) from Mailbox servers through ports 389,3268,636,3269 and worked fine but on port 390 no reply in both Mailbox servers, so what is caused on of our mailboxes to give the above error while the other one doesn't? Regards Suhaib Alnoursi

Hi, Please read the following articles from another site: Sven Jaanson (Last update 2/7/2008): In my case, this error disappeared after defining the WINS server in the Exchange server network properties. Zahar Celac (Last update 11/4/2007): In my case this error appeared after applying Update Rollup 5 for Exchange Server 2007 (see M941421). The mailbox database became dismounted, so I just mounted it manually. Anonymous (Last update 7/26/2007): In my case for Exchange 2007, the Information Store was starting before the System Attendant and it could not read from my Global Catalog server. I changed the following in the registry: - Add MSExchangeSA to DependOnService at HKLM\System\CurrentControl Set\Services\MSExchangeIS. The errors never appeared again. Anonymous (Last update 4/11/2007): In my case, the problem was caused by a corrupted scheme in AD. On Exchange 2007 DVD, I ran setup.exe /p to recreate the scheme. The error messages stopped and nothing was lost. The queued messages were then delivered. I hope this will help you if net than please let me know Regards. Shafaquat Ali. M.C.I.T.P Exchange 2007/2010, M.C.I.T.P Windows Server 2008, M.C.T.S OCS Server 2007 R2, Phone: +923008210320